The present invention relates to compositions and methods for improving performance of breeding populations of swine, in particular by increasing reproductive performance. These improvements enhance commercial value of swine populations. More particularly, this invention is directed to administration to both sows and boars of a feed composition containing marine animal products from which are derived long chain omega-3 fatty acids, such as eicosapentaenoic acid, docosahexaneoic acid, and docosapentaenoic acid, to increase the reproductive performance of breeding populations of swine.
Omega-3 and omega-6 fatty acids and their metabolites regulate numerous activities in vivo, including inflammation, disease resistance, platelet function and vessel wall contractions. Moreover, supplementation of omega-3 fatty acids and/or gamma-linolenic acid present in the diet of animals and humans are reported to have favorable effects on growth, heart disease, inflammatory and autoimmune disorders, diabetes, renal disease, cancer, and immunity as well as learning, visual acuity and neurological function.
On a cellular level long chain omega-3 fatty acids are readily incorporated into the phospholipid fraction of cell membranes where they influence membrane permeability/fluidity and transport. This represents a storage form of these fatty acids, where they remain until acted upon by phospholipase enzymes which release them for further conversion to eicosanoids.
Linoleic and alpha-linolenic acids are C18-containing fatty acids that are parent compounds of the omega-6 and omega-3 families of fatty acids, respectively. Omega-3 and omega-6 fatty acids undergo unsaturation (i.e., adding double bonds) and sequential elongation from the carboxyl end (i.e., adding 2-carbon units) with the D6-desaturase enzyme being the rate limiting enzyme in metabolism of these long chain fatty acids. The same enzymes are used for these families, making the families antagonistic to one another. Such antagonism, resulting from requirements for the same enzymes, extends into the further metabolism of the C20-containing members of these families into metabolites called eicosanoids.
The polyunsaturated fatty acids, including omega-3 and omega-6 fatty acids, differ from the other fatty acids in that they cannot be synthesized in the body from saturated or monounsaturated fatty acids, but must be obtained in the diet. The omega-6 fatty acid, linoleic acid, is found in high quantities in vegetable oils such as corn, cottonseed, soybean, safflower and sunflower oil. The omega-3 fatty acid, alpha-linolenic acid, is found in high quantities in flaxseed oil, linseed oil, perilla oil and canola oil. Other important compounds include arachidonic acid, found in animal fat; gamma-linolenic acid, found in evening primrose oil, borage oil, and blackcurrant oil; and eicosapentaenoic acid, docosahexaenoic acid, and docosapentaenoic acid derived from fish oils and marine algae. These long-chain fatty acids can be formed in the body by elongation and desaturation of the parent linoleic and alpha-linolenic acids if the parent compounds are supplied in the diet.
Various oils have been used as sources of omega-3 and omega-6 fatty acids in animal feed. The lactational responses of dairy cows fed unsaturated fat from extruded soybeans or sunflower seeds have been studied (Schingoethe, et al., 1996); flaxseed oil has been used in animal feed to increase the number of live births in sows, to increase the number of live weaned pigs, and to allow for earlier breeding (U.S. Pat. No. 5,110,592); conjugated linoleic acid has been used in animal feed to increase fat firmness, shelf life, and meat quality (U.S. Pat. No. 6,060,087); linseed oil and corn oil have been used in animal feed as a source of omega-6 fatty acids to increase the number of live births and to increase the number of weaned rats (Quackenbush, et al., 1942); salmon oil has been used in pet food to reduce damage to skin and mucosa in animals, such as dogs and cats, where the animal is afflicted with cancer and is subjected to radiation therapy (U.S. Pat. No. 6,015,798); the effects of linseed oil, and omega-3 fatty acids in particular, on increased sperm fertility and female fertility, applicable to cattle, sheep, and rats, has been studied (Abayasekara, et al., 1999); modified tall oil supplemented swine animal feed has been used to improve the carcass characteristics of swine and to increase daily weight gain (U.S. Pat. No. 6,020,377); the use of salmon oil to increase sperm fertility in roosters using a 1.5:1 ratio of omega-6 fatty acids to omega-3 fatty acids has been studied (Blesbois, et al., 1997), and the effect of dietary fatty acids on lactic acid bacteria associated with the epithelial mucosa has been studied (Ringo, et al., 1998).